Embodiments of the present disclosure provide methods for patterning a hardmask layer disposed on a metal layer, such as a copper layer, to form an interconnection structure in semiconductor devices. In one embodiment, a method of patterning a hardmask layer on a metal layer disposed on a substrate includes supplying a first etching gas mixture comprising a carbon-fluorine containing gas and a chlorine containing gas into a processing chamber to etch a portion of a hardmask layer disposed on a metal layer formed on a substrate, supplying a second etching gas mixture comprising a hydrocarbon gas into the processing chamber to clean the substrate, and supplying a third etching gas mixture comprising a carbon-fluorine containing gas to remove a remaining portion of the hardmask layer until a surface of the metal layer is exposed.
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1. A method of patterning a hardmask layer disposed on a metal layer formed on a substrate, comprising: supplying a first etching gas mixture comprising a first carbon-fluorine containing gas and a chlorine containing gas into a processing chamber to etch a portion of the hardmask layer disposed on the metal layer formed on the substrate; subsequently supplying a second etching gas mixture comprising a hydrocarbon gas without the first carbon-fluorine containing gas and the chlorine containing gas from the first etching gas mixture into the processing chamber for a first period of time without applying RF source power or RF bias power to clean the hardmask layer and the substrate disposed in the processing chamber; and subsequently supplying a third etching gas mixture that is different from the first etching gas mixture, the third etching gas mixture comprising a second carbon-fluorine containing gas to continue removing a remaining portion of the hardmask layer until a surface of the metal layer is exposed.
A method patterns a hardmask layer on a metal layer on a substrate to create interconnection structures. First, a carbon-fluorine gas and chlorine gas mixture etches part of the hardmask. Next, a hydrocarbon gas mixture, without the carbon-fluorine or chlorine gases, cleans the hardmask and substrate without applying RF power. Finally, a different carbon-fluorine gas mixture removes the remaining hardmask until the metal layer is exposed. This multi-step etching process aims to selectively remove the hardmask while minimizing damage to the underlying metal.
2. The method of claim 1 , the metal layer is a copper layer.
The metal layer in the hardmask patterning method is made of copper. This specifically targets the creation of copper interconnects, a common material for conductive pathways in semiconductor devices. The method, involving etching with carbon-fluorine and chlorine gases, followed by hydrocarbon cleaning, and a final carbon-fluorine etch, is used to pattern the hardmask layer on the copper layer.
3. The method of claim 1 , wherein the hardmask layer is a Ta containing material or a Ti containing material.
The hardmask layer in the patterning method uses a material containing either tantalum (Ta) or titanium (Ti). The method, involving etching with carbon-fluorine and chlorine gases, then cleaning with hydrocarbon gas without RF power, and finally etching with carbon-fluorine gas, is used to selectively remove the hardmask while minimizing damage to the underlying metal layer.
4. The method of claim 1 , wherein supplying the first etching gas mixture further comprising: etching the hardmask layer to a depth of between about 50 percent and about 90 percent of a total thickness of the hardmask layer.
During the initial etching of the hardmask layer using a carbon-fluorine and chlorine gas mixture, the method removes between 50% and 90% of the hardmask layer's total thickness. The method then cleans the substrate with a hydrocarbon gas and finishes by etching the remainder of the hardmask with another carbon-fluorine gas. Controlling the initial etch depth is important for precise pattern transfer.
5. The method of claim 1 , further comprising: applying a RF source power or a RF bias power to the second gas mixture for a second period of time after the first period of time.
After cleaning the substrate with a hydrocarbon gas mixture (without RF power) in the hardmask etching method, RF source power or RF bias power is applied to the second gas mixture for a period of time. The initial hydrocarbon gas cleaning removes etching byproducts. Applying RF power after cleaning can help further refine the etched profile before the final hardmask removal. The subsequent etching removes the remaining hardmask.
6. The method of claim 1 , wherein the hydrocarbon gas supplied in the second gas mixture is selected from a group consisting of methane (CH 4 ), ethane (C 2 H 6 ), propane (C 3 H 8 ), butane (C 4 H 10 ), pentane (C 5 H 12 ), hexane (C 6 H 14 ), propene, ethylene, propylene, butylene, pentene and combinations thereof.
The hydrocarbon gas used in the cleaning step of the hardmask etching method can be selected from methane (CH4), ethane (C2H6), propane (C3H8), butane (C4H10), pentane (C5H12), hexane (C6H14), propene, ethylene, propylene, butylene, pentene, or combinations thereof. The method involves etching with carbon-fluorine and chlorine, hydrocarbon cleaning, and a final carbon-fluorine etch, aiming to selectively remove the hardmask.
7. The method of claim 1 , wherein the hydrocarbon gas supplied in the second gas mixture is methane (CH 4 ).
The hydrocarbon gas supplied during the cleaning step of the hardmask etching method is specifically methane (CH4). The method involves first etching the hardmask with a carbon-fluorine and chlorine gas mixture, then cleaning with methane (CH4) without RF power, and finally etching with a different carbon-fluorine gas mixture. The methane cleaning step removes etching byproducts before the final etch.
8. The method of claim 1 , wherein the first and the second carbon-fluorine containing gas supplied in the first and the third gas mixture is selected from a group consisting of CFH 3 , CF 2 H 2 , CF 3 H, C 2 F 2 H 4 , C 2 F 2 H 6 , CF 4 and C 2 F 6 .
The carbon-fluorine containing gas used in both the initial etch and the final etch of the hardmask etching method is selected from CFH3, CF2H2, CF3H, C2F2H4, C2F2H6, CF4, and C2F6. This selection offers flexibility in controlling etch rates and selectivity during the hardmask patterning process. The method cleans with a hydrocarbon gas between the two etching steps.
9. The method of claim 8 , wherein the first carbon-fluorine containing gas supplied in the first gas mixture is CF 3 H.
The carbon-fluorine containing gas used in the *first* etching step of the hardmask etching method is specifically CF3H. The initial etch removes most of the hardmask layer using a carbon-fluorine (CF3H) and chlorine gas mixture, followed by hydrocarbon cleaning without RF power, and a final etch with a different carbon-fluorine gas. This specific gas combination is used for the first etching step.
10. The method of claim 8 , wherein the second carbon-fluorine containing gas supplied in the third gas mixture is CF 4 .
The carbon-fluorine containing gas used in the *third* etching step of the hardmask etching method is specifically CF4. The hardmask is first etched with carbon-fluorine and chlorine, then cleaned with hydrocarbon, and lastly etched with CF4 to remove the remaining material. This specific gas combination is used for the final etching step.
11. The method of claim 1 , wherein the chlorine containing gas supplied in the first gas mixture is Cl 2 gas.
The chlorine containing gas supplied in the *first* gas mixture during the initial etching step of the hardmask etching method is chlorine gas (Cl2). The first step etches the hardmask with carbon-fluorine and Cl2. This is followed by hydrocarbon cleaning and then a final carbon-fluorine gas etch.
12. The method of claim 1 further comprising: performing an ashing process to remove etching byproducts from the substrate surface.
After the three main etching steps (carbon-fluorine/chlorine etch, hydrocarbon clean, carbon-fluorine etch), an ashing process removes etching byproducts from the substrate surface. This additional step helps to improve the cleanliness and quality of the final patterned structure after the hardmask is removed.
13. The method of claim 12 , wherein the ashing process comprises supplying a H 2 gas into the processing chamber.
The ashing process performed to remove etching byproducts involves supplying hydrogen gas (H2) into the processing chamber. The H2 gas reacts with the remaining byproducts to form volatile compounds, which are then removed from the chamber. This cleaning process is performed after the hardmask layer is patterned.
14. The method of claim 1 , wherein the second etching gas mixture further comprises an oxygen containing gas.
The second etching gas mixture (the cleaning step) in the hardmask etching method further includes an oxygen-containing gas in addition to the hydrocarbon gas. The hydrocarbon and oxygen mixture removes etching residuals from the substrate surface before the final etch.
15. The method of claim 14 , wherein the hydrocarbon gas and the oxygen containing gas is supplied at a ratio between about 10:1 and about 5:1.
The hydrocarbon gas and the oxygen-containing gas in the cleaning step of the hardmask etching method are supplied at a ratio between 10:1 and 5:1. This ratio controls the effectiveness of the cleaning process in removing residual etching byproducts. The method includes an initial carbon-fluorine/chlorine etch, the hydrocarbon/oxygen clean, and then a final carbon-fluorine etch.
16. A method of patterning a hardmask layer disposed on a metal layer formed on a substrate, comprising: performing an etching break-through process to etch a depth of the hardmask layer disposed on the metal layer formed on the substrate, wherein the depth of the hardmask layer is between about 50 percent and about 90 percent of a total thickness of the hardmask layer, wherein the hardmask layer is a Ta containing material or a Ti containing material, wherein the hardmask layer is etched by a chlorine free carbon-fluorine containing gas; subsequently performing a flash cleaning process to remove etching residuals from the substrate without the chlorine free carbon-fluorine containing gas and without applying RF source power or RF bias power during the flash cleaning process; and subsequently performing an interface cleaning process to continue etching a remaining portion of the hardmask layer from the substrate, wherein the interface cleaning process uses a first gas mixture that is different from a second gas mixture supplied in the etching break-through process.
A method patterns a hardmask layer (made of Ta or Ti containing material) on a metal layer by performing an etching break-through process that etches 50-90% of the hardmask using a chlorine-free carbon-fluorine gas. Then, a flash cleaning process removes etching residuals without using the chlorine-free carbon-fluorine gas and without applying RF power. Finally, an interface cleaning process etches the remaining hardmask using a different gas mixture than the break-through process.
17. The method of claim 16 , wherein the interface cleaning process is performed by supplying the first etching gas mixture including a hydrogen free carbon-fluorine containing gas.
The interface cleaning process (the final hardmask removal step) in the hardmask patterning method involves supplying a first etching gas mixture that includes a hydrogen-free carbon-fluorine containing gas. The method consists of an initial breakthrough etch with chlorine-free carbon-fluorine gas, then a flash clean, and finally the interface cleaning with hydrogen-free carbon-fluorine gas.
18. The method of claim 16 , wherein the flash cleaning process comprises supplying a gas mixture including a hydrocarbon gas and an oxygen containing gas supplied at a ratio between about 10:1 and about 5:1.
The flash cleaning process, used to remove etching residuals in the hardmask patterning method, uses a gas mixture including a hydrocarbon gas and an oxygen-containing gas, supplied at a ratio between 10:1 and 5:1. This cleaning step occurs between an initial hardmask breakthrough etch and a final interface cleaning etch to improve the surface quality.
19. A method of patterning a hardmask layer disposed on a metal layer formed on a substrate, comprising: performing an etching break-through process by supplying a first gas mixture to etch a depth of the hardmask layer disposed on the metal layer formed on the substrate, wherein the depth of the hardmask layer is between about 50 percent and about 90 percent of a total thickness of the hardmask layer, the first gas mixture including a carbon-fluorine containing gas and a chlorine containing gas; subsequently performing a flash cleaning process to remove etching residuals from the substrate by supplying a second gas mixture including a hydrocarbon gas without the carbon-fluorine containing gas and the chlorine containing gas from the first gas mixture and without applying RF source power or RF bias power; and subsequently performing an interface cleaning process to continue etching a remaining portion of the hardmask layer from the substrate by supplying a third etching gas mixture including a hydrogen free carbon-fluorine containing gas while maintaining the substrate temperature at about 90 degrees Celsius.
A method patterns a hardmask layer on a metal layer using an etching break-through process, a flash cleaning process, and an interface cleaning process, where the substrate temperature is maintained at 90 degrees Celsius. The etching break-through process etches 50-90% of the hardmask using a carbon-fluorine and chlorine gas mixture. Then, a flash cleaning process removes etching residuals using a hydrocarbon gas mixture without the carbon-fluorine and chlorine gases, and without applying RF power. Finally, the remaining hardmask is etched by supplying a hydrogen-free carbon-fluorine gas mixture.
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September 24, 2014
May 16, 2017
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